When pain is localized to the foot but no abnormalties can be seen on radiographs (often called X rays), problems in soft tissues within the foot are often the culprit. However, imaging soft tissues in the foot to arrive at a diagnosis can be challenging, especially when magnetic resonance imaging (MRI) is not available or financially feasible. At the 2010 American Association of Equine Practitioners Convention, held Dec. 4-8 in Baltimore, Md., one veterinarian discussed the use of ultrasound as a lower-cost option for imaging soft tissue problems in the hoof.
There is a small hypoechoic (black) round lesion on the dorsal aspect of the lateral lobe (on the right of the image) of the tendon (arrow) visible in this transverse ultrasound images of the deep digital flexor tendon.
Denis Verwilghen, DVM, MSc, DES, Dipl. ECVS, specialist in equine and large animal surgery at the University of Liège in Belgium, discussed findings in 39 horses with this presentation, reporting that veterinarians using ultrasound examination were able to identify specific soft tissue problems in all cases. The most common issues were deep digital flexor tendon lesions (30 horses), followed by abnormalities in the coffin joint and associated ligaments (27 horses), and distension of the navicular bursa (22 horses).
All but three horses had abnormalities of multiple structures within the foot detectable with ultrasound, highlighting the often complex nature of lameness diagnosis.
"Ultrasound allowed documentation of digital soft tissue injuries, especially deep digital flexor tendinopathy (disease of a tendon), in horses without radiographic findings," Verwilghen concluded. "The distribution of findings was similar to previous MRI studies. Ultrasound can provide a diagnosis of foot pain of MRI is not available or possible financially."
Valeria Busoni , DVM, PhD, Dipl. ECVDI, specialist in diagnostic imaging at the University of Liège, added: "Ultrasound examination of the foot requires practice and experience as it is more technical compared to a routine tendon ultrasound. Moreover, the approach through the bulbs of the heels (which is the one that shows most deep digital flexor tendon lesions) requires a microconvex probe, which is not the probe routinely used to image tendons. So equine practitioners willing to apply this technique to the foot have to be equipped and trained to perform foot ultrasound."
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.